Regulatory Impact to the Design of Plants in

by Ami Rastas Consultant

Nuclear-electricity in Chile: How far, How close. International Seminar on Possibilities, Gaps and Challenges January 28th, 2010 Hyatt Hotel, Santiago, Chile.

1 QUESTIONS TO BE ADDRESSED

The Finnish case:

 How a strong regulatory body can trigger technical innovations on the reactors' design?

 Importance of having the required human resource in the regulatory body?

The questions will be addressed based on my former experience bu ilt up as an emp loyee (re tire d) o f TVO tha t is the owner/operator of the Olkiluoto .

2 CONTENTS

• Status of • Finnish nuclear safety regulations • Examples of regulatory impacts to the design of the existing nuclear power plants in Finland • Finnish influence in the development of new plant designs • Examples of regulatory impacts to the Olkiluoto 3 plant unit • Organization and staff of the regulatory body STUK • Technical and scientific support • Conclusions

3 STATUS OF NUCLEAR POWER IN FINLAND

 Four nuclear power plant units in operation, one unit under const ruct io n a nd t he ne xt u nit(s) in th e earl y ph ase of licensing

 Extensive modernization projects (including power uprating) completed for each existing unit in the late 90’s

 Operational results of the existing units very favourable  Life time load factors until the end of 2009 – plant (LO1 and LO2) 87.7 % – Olkiluot o pl ant (OL1 and OL2) 93. 0 %

 Advanced nuclear waste management program and funding system

4 NUCLEAR POWER PLANTS IN FINLAND

Olkiluoto Loviisa OL1 BWR 860 MW 1978 LO1 PWR 488 MW 1977 OL2 BWR 860 MW 1980 LO2 PWR 488 MW 1979 OL3 PWR 1600 MW 2012

Teollisuuden Voima Oyj Power and Heat Oy (TVO) (FPH, prev ious IVO) Olkiluoto Loviisa

5 6 STUK’S ROLE IN PREPARATION OF NUCLEAR SAFETY LEGISLATION AND REQUIREMENTS

• Nuc lear Energy Ac t an d Nuc lear Energy Decree (1957, la tes t rev is ion 2008) – preparation coordinated by Ministry (MEE), STUK provides input to safety reltdlated par ts • Government Decisions (1991, revised to be Decrees 2008) – four separate Decrees: safety of NPPs, physical protection of NPPs, emergency preparedness, safety of the disposal of nuclear waste – drafts written by STUK, final format given by Ministry (MEE) • YVL Guides issued by STUK – detailed requirements for plant design and licensing process – prepared by STUK in close co-operation with relevant stakeholders – overall reform of YVL Guides initiated in 2006 and continues until 2011 – YVL Guides are to be applied as such to new nuclear power plants, application to plants in operation or under construction is considered case by case

7 FINNISH NUCLEAR LICENSING PROCESS

OPERATING LICENSE CONSTRUCTION PERMIT Government DECISION IN PRINCIPLE ENVIRONMENTAL Government IMPACT Government ASSESSMENT Parliament Ministry of Employment and Economy

8 DEVELOPMENT OF SAFETY REQUIREMENTS IN FINLAND

• The need for Finnish nuclear safety requirements arose in 1970 when a decision to buy a Soviet designed NPP had been made (Loviisa, VVER- 440) • STUK has since then developed and updated national safety requirements • SftSafety requi rement s are b ased on we ll es tblihdtablished na tiona l an d international practices - IAEA Safety Standards are becoming increasingly important • The leading principle has been to incorporate the state-of-the-art in the nuclear safety technology into the safety requirements - oppgperating experience - research - development of science and technology

9 GENERAL PRINCIPLES APPLIED IN FINNISH SAFETY REQUIREMENTS FOR DESIGN (1/2) • The nuclear safety philosophy applied worldwide since late 1960’s has been 100% successful at commercial nuclear power plants  there has never been a large radioactive offsite release at plants which apply this philosophy

• It is well -founded to keep safety requirements based on this successful philosophy  the core of the safety philosophy consists of the defence-in-depth principle and deterministic postulation of certain design basis accidents

• As a necessary complement to the deterministic safety design, a probabilistic risk analysis (PRA) is required to be presented for getting Construction Permit and has to be kept up-to-date since then. Risk informed approach to safety strengthens the traditional design practice.

10 GENERAL PRINCIPLES USED IN FINNISH SAFETY REQUIREMENTS FOR DESIGN (2/2)

• Safety requirements are performance based, as opposite to being prescriptive • Consequently, there are several expressions that in some other countries could be considered to cause “regulatory uncertainty”: . “as necessary”“, take into account…,”“ adequately”“, as appropriate”, “suitable”, “as far as possible”, … • Successful use of this type of requirements demands . high technical knowledge of the regulatory staff . mutual trust and common understanding on acceptable safety level among the involved parties (vendor, licensee, regulator)

11 EXAMPLE OF DESIGN BASIS ACCIDENTS: LOSS OF COOLANT ACCIDENTS

Postulated loss-of-coolant accidents (e.g. pipe breaks) are important for defining the design targets for fuel, reactor core, mechanical structures, and safety systems, as well as for setting respective operational limits for them.  Systems designed for protection against loss-off-coolant accidents, shall be able to carry out their functions even though an individual component in any system would fail to operate and additionally any component affecting the safety function would be out of operation simultaneously due to repairs or maintenance . (N+2 redundancy is needed. )

12 FEATURES REQUIRED TO PREVENT RADIOACTIVE RELEASES FROM A SEVERE ACCIDENT

• Containment integrity must be protected by dedicated systems designed to take into account core meltdown related phenomena  hig h pressure fa ilure o f reac tor vesse l preven te d by de dica te d depressurization system  hydrogen management with autocatalytic recombiners to prevent detonation  low pressure melt arrested in a core catcher, with passive long- term cooling  containment integgygrity against d ynamic loads  containment pressure management in long term  containment leak tightness criteria from release limits • FtdidfttiitFor systems designed for protection against severe accid idtilents, single failure criterion (N+1 redundancy) applies. Those systems have to be independent from the safety systems for design bases accidents.

13 PROTECTION AGAINST EXTERNAL THREATS

After Sepp,pptember 11, 2001: political and public will was expressed to improve protection against terrorist actions. Safety requirements were revised accordingly:

 Crash of large passenger and military aircraft has to be taken into account in the design  no immediate release of significant amount of radioactive substances  initiation and maintenance of key safety functions in spite of the direct consequences of the event (penetration of structures by impacting parts, vibration, explosion, fire)  Plant has to be protected against microwave and biologic weapons.

14 EXAMPLES OF LOVIISA 1 AND 2 DESIGN MODIFICATIONS

• The original Sovjet VVER 440 design was supplemented already in the beginning with the reactor containment, emergency cooling systems and I&C systems fulfilling the Western safety requirements. • Arrangements to cope core meltdown accidents have been implemented (inside reactor vessel retention approach) a couple of years ago. • Modernization of I&C systems is in progress (digital I&C).

15 EXAMPLES OF OLKILUOTO 1 AND 2 DESIGN MODIFICATIONS

• Arrangements (thermal protection of the lower part of the containment, flooding of molten core, filtered containment venting, containment fill-up) to cope with core meltdown accidents were implemented in the late 80’s.

• An extensive modernization program including safety uppgrading and power uprating was carried in the late 90’ s interlinked with the operation license renewal.

16 OLKILUOTO 1 AND 2 – ARRANGEMENTS FOR SEVERE ACCIDENTS

17 MAIN MOOCOSDIFICATIONS INPLEMENTED DU UGRING THE MODERNIZATION OF OLKILUOTO 1 AND 2 IN 1994-1998

New LP-turbines (n. +35 MW) Reactor power New safety analyses, 2160 -> 2500 MWt upgrading of safety Modification of HP-turbine Modifications of reheaters systems New turbine control/safety system New generator New HP-control/ New loading machine automation safety valves 710 -> ca 840 MWe New steam separators/ scroud head New generator circuit breaker

New type of fuel (10x10) New main transformer 2 new safety/reliefvalves

Strengthening of the outer grid Upgrading of boron system

New moisture separators (SCRUPS) to cross under New electrical pipes and process modifications systems of reactor internal pump

Modifications of preheaters New neutron flux Modificatons of condensate Improvements of waste and measuring system and feed water pumps waste water treatment systems

18 DEVELOPMENT OF NEW PLANT DESIGNS

• Finnish utilities participated in the development of new plant designs in the 1980s-1990s

• Fortum: VVER 1000, AP1000 • TVO: BWR 90/90+, ESBWR, SWR 1000 (Kerena)

• One reason for the participations was to influence to the plant concepts so that they would meet the Finnish safety requirements.

19 FEASIBILITY STUDIES FOR FIN5

• As a preparatory step for FIN5 (later Olkiluoto 3), TVO carried out in cooperation with corresponding vendors feasibility studies for three BWR designs (ABWR, BWR90+, SWR1000) and for three PWR designs (AP1000, EPR, VVER1000) in 1998-2000. • One of the main goals of the feasibility studies was to find out discrepancies between the plant designs and the Finni sh saf et y requi rement s. • Several presentations on each plant design were made for STUK. • None of the original designs was licensable in Finland as such without design modifications. • Needed modifications in each design were drafted.

20 DECISION IN PRINCIPLE ON FIN5

• In TVO’s application (Nov. 2000) for the Decision In Principle (DIP) for FIN5, the plant designs studied in the Feasibility Studies were presented as possible alternatives to be constructed. • STUK made a preliminary safety assessment on each design and ended up to the following general statement:

“The preliminary safety assessment of STUK has not brought up matters, w hich would prove th at th e pl ant opti ons, presen te d in the application for a decision in principle, could not be made to fulfill the Finnish safety regulations. None of the presented options does, however, meet all the requirements as such. The nature and/or extent of the necessary modifications vary considerablyyyp by plant t ypes.“

21 FIN5 BIDDING PROCESS

• TVO prepared th e t ech ni cal Bid Inv ita tion Specifications (BIS) based on the European Utility Requirements (EUR) document. • The safety related requirements were modified to be consistent with the Finnish requirements. • The safety related parts of the draft BIS was send for review to STUK . STUK’s comments were taken into account in the final BIS. • TVO send the BIS to the Bidders in September 2002, received the bids in March 2003, evaluated FIN5 BIS the bids and signed the turnkey delivery contract on the EPR in December 2003. • Several three ppyarty meetin g(gs (Bidder/TVO/STUK ) arranged during the bid evaluation phase in order to find out the licensability of the proposed designs.

22 EXAMPLES OF EPR SAFETY FEATURES

23 EXAMPLES OF EPR DESIGN CHANGES FROM FEASIBILITY STUDY TO CONTRACT • Outer reactor containment and safety system buildings were stthdtidtrengthened to provide prottitection agai itilnst airplane crash • Inner containment was equipped with steel liner to ensure its adequate leak tightness •Design features for severe accident management were improved (molten core management, hydrogen management, high pressure melt prevention) •priiitlimary circuit loops were prov iddided pihititipe whip restraints designed to restrict leak flow area in case of large LOCA • in addition to the two diverse digital reactor protection systems, most important protection signals have hard wired back up

24 2 Figures indicate staff number 5 STUK’ S ORGANISATION at the end of 2008. Total 361.

Nuclear Waste and Materials DG's office 9 Regulation 25

Nuclear Reactor Regulation 99 Public RditiRadiation Prac tices RltiRegulation Communication 4 44

Emergency Research and Environmental PdPreparedness 4 Surveillance 97

Expert Services Non-ionising Radiation 8 10

Administration, Internal Services and Information Management 61

25 ORGANIZATION OF REGULATION DIVISION

Director

Deputy Directors

26 NUMBER OF PERSONS AT THE NUCLEAR REACTOR REGULATION DIVISION (end of each year)

120

99 100 88 86 83 80 76 68

r 61 62 60 numbe

40

20

0 2001 2002 2003 2004 2005 2006 2007 2008

27 EDUCATIONAL LEVEL OF STUK ’ S STAFF at the end of 2008

Basic education Doctor 4.8 % PhD Vocational school 11.9 % 10.4 % Licentiate Technicians 4.8 % 9.8 %

Engineer Lower university Diploma engineer decree MSc 12.5 % 45.8 %

28 TECHNICAL SUPPORT OF STUK

• STUK has tight relations to national and international Technical Support Organizations (TSOs), such as  Technical Research Centre of Finland (VTT)  IRSN (France)  ISaR (Germany) • TSOs are contracted to make independent confirmatory analysis or experimental research on topics requiring specific in-depth knowledge. • STUK has co-operation arrangements with several foreign regulatory bodies, such as  ASN (France),  NRC (USA)  Rostechnadzor (Russia),  SSM (()Sweden)

29 SCIENTIFIC SUPPORT OF STUK

• National nuclear safetyyg research has been organized since the 1980’s into research programs with 3-4 years duration. • Programs are planned and conducted in co-operation between Ministry, STUK, utilities, research institutes and universities. • The present program SAFIR2010 includes 33 research projects covering the following areas: 1. Organization and human factors 2. Automation and control room 3. Fuel and reactor physics 4. Thermal hydraulics 5. Severe accidents 6. Struct ural saf et y of react or ci rcuit 7. Construction safety 8. Probabilistic safetyyy( analysis (PSA))

30 CONCLUSIONS

• The nuclear legislative framework in Finland has a long history and has been updated when needed. • STUK has a competent staff and effective relations to support organizations to develop safety requirements, to assess nuclear power plant designs and to achieve effective regulatory control of nuclear plant construction and operation. • Generally, there is mutual understanding and respect between STUK and the licensees. A frank and open relationship is beneficial for tackling safety issues in order to achieve and maintain a high level of safety. • The safety requirements imposed by STUK have influenced considerably to the design of the plants in operation and under construction in Finland.

31 THANK YOU FOR YOUR ATTENTION!

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